Many of the next generation flexible printed electronic displays such as organic light emitting diodes (OLEDs), organic photovoltaic displays (OPVs), organic thin film transistors (OTFTs), etc., are extremely sensitive to atmospheric moisture vapor and oxygen, which limits the lifetime of the display devices and their widespread commercialization.
The current encapsulation technology generally available in the field or moisture sensitive organic electronic devices is a glass lid with a getter material fixed to the substrate by epoxy glue. The getter materials, such as, e.g., calcium oxide or barium oxide, are incorporated into the package to react with any byproducts of the resin cure process or any residual water incorporated in the package or diffusing through the epoxy seal over time. Although the glass has been used prevalently as an encapsulant or barrier layer due to its low permeability to water vapor and oxygen transmission, the main drawback with glass encapsulated technology is that the resultant devices become non-flexible and rigid, which cannot satisfy the applications demanding flexible devices.
Several attempts have been made to develop flexible barrier films. These include multilayer systems of alternating inorganic and organic layers (often more than 10 layers). Such systems are described in, for example, WO 00/36665 A1, WO01/81649 A1, WO 2004/089620 A2, WO 03/094256 A2, and WO2008/057045 A1. Although, the multilayer thin film technology provides good barrier properties and serves the purpose of encapsulation to the electronic devices, the complex nature and high cost of thin film preparation do not make them feasible in large area and large scale manufacturing processes. It is therefore desirable to provide substrates with improved barrier properties that can protect the display devices from the premature deterioration and extend their lifetimes.